Selective enucleation (SE) was applied to germinal vesicle (GV) oocytes by removing the chromatin attached to nuclear envelope, and leaving the liquid contents of GV in the cytoplast. However, after reconstruction with 1/8 blastomeres or fetal fibroblasts (FFs) neither the maturation efficiency nor the frequency of normal (asymmetric) division was improved as compared with completely enucleated (CE) oocytes. Chromosomal aberrations introduced with somatic nuclei were not rescued in SE oocytes either. On the other hand, timing of maturation division in SE GV oocytes, but not in CE GV oocytes, reconstructed with GV-karyoplasts was like in the control. After maturation and fertilization in vitro, SE oocytes reconstructed with 1/8 blastomeres developed nucleolated donor pronuclei, contrary to CE oocytes. The latter could be rescued with nucleoli-containing nucleus, but not anucleolate nucleus, from a 1/2 blastomere. SE oocytes reconstructed with FFs contained nucleolated pronuclei upon activation, unlike CE GV oocytes. These experiments show that the ooplast nucleolar material and/or embryonic nucleolus are indispensable for pronuclei formation. SE oocytes reconstructed with 1/8 blastomeres or FFs failed to cleave after activation or in vitro fertilization. Control GV oocytes enucleolated before fertilization seized cleavage at the 6-cell stage, as oppose to intact GV oocytes, which in 50.9% yielded morulae/blastocysts. These results suggest that ooplast nucleolar material is essential for the cleavage divisions. Activation of cumulus-enclosed SE GV oocytes matured in hormone-supplemented medium and fused to 1/2 blastomere-karyoplasts, yielded morulae, and blastocysts in 45.5% and 23.4% of reconstructed oocytes, respectively.

This study examined the effects of a dietary synbiotic supplement on the behavioral patterns and growth performance of broiler chickens exposed to heat stress (HS). Three hundred sixty 1-day-old male Ross 708 broiler chicks were distributed among 24 floor pens (15 chicks per pen); each pen was randomly assigned to one of 3 dietary treatments containing a synbiotic at 0 (control), 0.5 (0.5X) and 1.0 (1.0X) g/kg. From d 15 to 42, birds were exposed to HS at 32°C daily from 08:00 to 17:00. Five broiler chickens were randomly marked in each pen for behavioral observation. Instantaneous scan sampling was used to record the birds' behavioral patterns. Performance parameters were measured on d 7, 14, 28 and 42. The synbiotic fed birds exhibited more standing, sitting, walking, feeding, preening and less wing spreading and panting behaviors (P < 0.05) compared to birds fed the control diet. The synbiotic group also had higher BW, BW gain and feed intake on d 7, 14 and 42 (P < 0.05), and higher BW, feed intake and feed conversion ratio at d 28 (P < 0.01). There were no treatment effects on drinking behavior, BW gain on d 28 and feed conversion ratio on d 42 (P > 0.05). There were few dose-related differences of the synbiotic on production performance; namely, the 1.0X concentration resulted in the highest BW and feed intake on d 14 and 42 (P < 0.05), while BW gain was higher compared to the control group only on d 42 (P < 0.05). The results suggest that the synbiotic supplement may prove to be an important management tool for the broiler industry to diminish the negative effects of HS, potentially safeguarding the welfare and production of broiler chickens, particularly in areas that experience hot climates.

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The objective of the study was to examine preimplantation development of the zygotes derived from bovine oocytes matured in the presence of follicular fluid (bFF) randomly pooled from large (>10 mm in diameter) highly vascularised ovarian follicles originating from slaughter-house ovaries. The maturation medium was supplemented with 20% bFF. The controls comprised 20% bFF+10% FCS, and 10% FCS.The use of three separate batches of bFF have shown that the rates of cleavage (78-87%) and blastocyst formation (about 40%) obtained after bFF-supplemented maturation are similar or higher than those in the FCS control. In another experiment morphological selection of Grade I oocytes was performed after maturation or insemination. Selection of Grade I matured oocytes increased cleavage rate (to 85-91%) and blastocyst yield (to 43%). When Grade I inseminated oocytes were selected, then 92-93% of zygotes divided, and 47% reached blastocyst stage. Blastocyst rates were higher after bFF-supplemented maturation than after FCS-supplemented one, both in Grade I matured (43.0 as opposed to 40.7%) and Grade I inseminated (47.3 against 45.8%) oocytes.The majority of all zygotes underwent the first cleavage division between 27 and 30 hpi. Zygotes originating from oocytes matured in the presence of bFF or bFF+FCS were found dividing until 48 hpi whereas those obtained from control oocytes no longer cleaved after 33 hpi.In conclusion, oocyte maturation in the presence of bovine bFF randomly pooled from large follicles of slaughter-house ovaries supports as high developmental capacity of presumed zygotes as does the FCS-control.KEY WORDS: bovine follicular fluid, in vitro maturation, in vitro insemination, cleavage, blastocyst rate

| The present study investigated the developmental competence of germinal vesicle (GV) oocytes and the resulting embryos upon dietary Dunaliella salina (DS) supplementation. Quality of GV oocytes and maturation, timing of zygotes cleavage to two-cell stage, quality of embryos and offspring number and weight were investigated of mice supplemented with DS (100g/kg ration; N=30) compared to control (N=30).Females were injected with 7.5 I.U. of equine chorionic gonadotropin (PMSG) followed by 7.5 I.U. of human chorionic gonadotropin (hCG) after 48h and mated with fertile male. Immature GV oocytes were harvested from ovaries after 48h of PMSG injection for investigating quality of oocyte, timing of breakdown of germinal vesicle (GVBD) and extrusion of first polar bodies and maturation rate (%).Zygotes were harvested from uterine tubes 29-30hafterhCG injection and followed for first cleavage whereas quality of blastocysts were evaluated after collection from uterine horn at96h of hCG. Improvement of oocyte quality has been indicated in DS group whereas GVBD and maturation rate were not differed between DS and control groups. Although D. salina did not change timing of first cleavage of zygotes, blastocysts' quality were significantly (P<0.05) increased in DS group. Furthermore, offspring number (9.9 ± 0.26 & 8.2 ± 0.30) and weight (12.01 ± 0.31 & 9.84 ± 0.37) at birth were increased significantly (P<0.05) in the DS group compared to control one. In conclusion, supplementation of D. salina could increase reproductive performance through improvement quality of germinal vesicle oocytes and preimplantation embryos.

Universal recipients in the G2 phase of mitotic cell cycle (preactivated oocytes, zygotes, blastomeres) accept embryonic nuclei in all the stages of their cell cycle. To test if recipients in the G2 of meiotic cycle (immature oocytes) are universal recipients, mouse germinal vesicle (GV) oocytes were enucleated and reconstructed with blastomere nuclei in the G1, S, or G2 stages. Analysis of their maturation has shown that about 30% of the G1 nuclei and 60% of G2 nuclei allow for normal metaphase II (MII), both in the oocytes with and without the first polar body (1st PB). Among oocytes reconstructed with the S phase nuclei, only 8% or less have normal MII, although 75% of them extrude 1st PB. No phase of donor cell cycle prevented the abnormal acceleration of 1st PB extrusion, found in reconstructed GV oocytes. In conclusion, enucleated GV oocytes are not universal recipients of embryonic nuclei, because they do not accept the S donors. However, both the G1 and G2 donor nuclei can be reprogrammed in the GV oocyte cytoplasm.

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